The daughtercard and the ChipQuik removal kit came in. In the videos below, I remove the 680LC040 and get the board ready for the 68040:

Tools and Planning:

Desoldering: (a bit long, due to fiddling with the flux and the actual chip removal)

Clean-up:

Review:

Note that I specifically chose not to use the hot-air rework station. I wanted to see if the 68LC040 could be removed with soldering iron and ChipQuik alone, as that would broaden the audience of those able to do the work. As it turns out, the hot-air station was not necessary, just patience in going over the leads enough to heat the whole chip.